source: trunk/www.guidonia.net/wp/wp-content/plugins/ferdinand-wordbook/phpthumb/phpthumb.ico.php@ 44

<?php
//////////////////////////////////////////////////////////////
///  phpThumb() by James Heinrich <info@silisoftware.com>   //
//        available at http://phpthumb.sourceforge.net     ///
//////////////////////////////////////////////////////////////
///                                                         //
// phpthumb.ico.php - .ICO output format functions          //
//                                                         ///
//////////////////////////////////////////////////////////////


class phpthumb_ico {

        function phpthumb_ico() {
                return true;
        }


        function GD2ICOstring(&$gd_image_array) {
                foreach ($gd_image_array as $key => $gd_image) {

                        $ImageWidths[$key]  = ImageSX($gd_image);
                        $ImageHeights[$key] = ImageSY($gd_image);
                $bpp[$key]          = ImageIsTrueColor($gd_image) ? 32 : 24;
                $totalcolors[$key]  = ImageColorsTotal($gd_image);

                        $icXOR[$key] = '';
                        for ($y = $ImageHeights[$key] - 1; $y >= 0; $y--) {
                                for ($x = 0; $x < $ImageWidths[$key]; $x++) {
                                        $argb = phpthumb_functions::GetPixelColor($gd_image, $x, $y);
                                        $a = round(255 * ((127 - $argb['alpha']) / 127));
                                        $r = $argb['red'];
                                        $g = $argb['green'];
                                        $b = $argb['blue'];

                                        if ($bpp[$key] == 32) {
                                                $icXOR[$key] .= chr($b).chr($g).chr($r).chr($a);
                                        } elseif ($bpp[$key] == 24) {
                                                $icXOR[$key] .= chr($b).chr($g).chr($r);
                                        }

                                        if ($a < 128) {
                                                @$icANDmask[$key][$y] .= '1';
                                        } else {
                                                @$icANDmask[$key][$y] .= '0';
                                        }
                                }
                                // mask bits are 32-bit aligned per scanline
                                while (strlen($icANDmask[$key][$y]) % 32) {
                                        $icANDmask[$key][$y] .= '0';
                                }
                        }
                        $icAND[$key] = '';
                        foreach ($icANDmask[$key] as $y => $scanlinemaskbits) {
                                for ($i = 0; $i < strlen($scanlinemaskbits); $i += 8) {
                                        $icAND[$key] .= chr(bindec(str_pad(substr($scanlinemaskbits, $i, 8), 8, '0', STR_PAD_LEFT)));
                                }
                        }

                }

            foreach ($gd_image_array as $key => $gd_image) {
                        $biSizeImage = $ImageWidths[$key] * $ImageHeights[$key] * ($bpp[$key] / 8);

                // BITMAPINFOHEADER - 40 bytes
                        $BitmapInfoHeader[$key]  = '';
                        $BitmapInfoHeader[$key] .= "\x28\x00\x00\x00";                              // DWORD  biSize;
                        $BitmapInfoHeader[$key] .= phpthumb_functions::LittleEndian2String($ImageWidths[$key], 4);      // LONG   biWidth;
                        // The biHeight member specifies the combined
                        // height of the XOR and AND masks.
                        $BitmapInfoHeader[$key] .= phpthumb_functions::LittleEndian2String($ImageHeights[$key] * 2, 4); // LONG   biHeight;
                $BitmapInfoHeader[$key] .= "\x01\x00";                                      // WORD   biPlanes;
                        $BitmapInfoHeader[$key] .= chr($bpp[$key])."\x00";                          // wBitCount;
                        $BitmapInfoHeader[$key] .= "\x00\x00\x00\x00";                              // DWORD  biCompression;
                        $BitmapInfoHeader[$key] .= phpthumb_functions::LittleEndian2String($biSizeImage, 4);            // DWORD  biSizeImage;
                $BitmapInfoHeader[$key] .= "\x00\x00\x00\x00";                              // LONG   biXPelsPerMeter;
                $BitmapInfoHeader[$key] .= "\x00\x00\x00\x00";                              // LONG   biYPelsPerMeter;
                $BitmapInfoHeader[$key] .= "\x00\x00\x00\x00";                              // DWORD  biClrUsed;
                $BitmapInfoHeader[$key] .= "\x00\x00\x00\x00";                              // DWORD  biClrImportant;
                }


                $icondata  = "\x00\x00";                                      // idReserved;   // Reserved (must be 0)
                $icondata .= "\x01\x00";                                      // idType;       // Resource Type (1 for icons)
                $icondata .= phpthumb_functions::LittleEndian2String(count($gd_image_array), 2);  // idCount;      // How many images?

                $dwImageOffset = 6 + (count($gd_image_array) * 16);
                foreach ($gd_image_array as $key => $gd_image) {
                // ICONDIRENTRY   idEntries[1]; // An entry for each image (idCount of 'em)

                $icondata .= chr($ImageWidths[$key]);                     // bWidth;          // Width, in pixels, of the image
                $icondata .= chr($ImageHeights[$key]);                    // bHeight;         // Height, in pixels, of the image
                $icondata .= chr($totalcolors[$key]);                     // bColorCount;     // Number of colors in image (0 if >=8bpp)
                $icondata .= "\x00";                                      // bReserved;       // Reserved ( must be 0)

                $icondata .= "\x01\x00";                                  // wPlanes;         // Color Planes
                        $icondata .= chr($bpp[$key])."\x00";                      // wBitCount;       // Bits per pixel

                        $dwBytesInRes = 40 + strlen($icXOR[$key]) + strlen($icAND[$key]);
                        $icondata .= phpthumb_functions::LittleEndian2String($dwBytesInRes, 4);       // dwBytesInRes;    // How many bytes in this resource?

                    $icondata .= phpthumb_functions::LittleEndian2String($dwImageOffset, 4);      // dwImageOffset;   // Where in the file is this image?
                        $dwImageOffset += strlen($BitmapInfoHeader[$key]);
                        $dwImageOffset += strlen($icXOR[$key]);
                        $dwImageOffset += strlen($icAND[$key]);
            }

            foreach ($gd_image_array as $key => $gd_image) {
                        $icondata .= $BitmapInfoHeader[$key];
                        $icondata .= $icXOR[$key];
                        $icondata .= $icAND[$key];
            }

            return $icondata;
        }

}

?>